This invention generally relates to connectors of the type used in the handling and administration of parenteral fluids and, more particularly, to a connector adapted to make sterile connections in medical systems without the use of a sharp cannula.
Injection sites for injecting or removing fluid from a system, such as an IV infusion set connected to a patient, or a fluid reservoir or drug vial, are wellknown and widely used. Conventional injection sites generally involve a pierceable septum formed of an elastomeric material such as latex rubber or the like, captured in an access port. The housing of the septum may be, for example, the Y-body of a conventional Y-site component of an IV delivery set. A sharp cannula is inserted into the access port, piercing the septum, and a distal end of the cannula is positioned distal of the septum. In this way a fluid connection is made with the Anterior of the access port through the inserted cannula. Upon withdrawal of the sharp cannula, the elastomeric septum reseals the puncture made by the now-withdrawn cannula. Thus a sterile environment can be maintained within the housing of the injection site. The outer surface of the septum of the injection site is wiped with an antiseptic before each use to prevent septic agents from being drawn into the access port by the piercing movement of the needle.
Recently, connectors for accommodating injection and withdrawal of fluids without the use of sharp cannulas have been used in increasing numbers instead of conventional injection sites. This is, at least in part, due to concern regarding the transmission of blood-borne diseases through accidental needle punctures of the person handling the sharp cannula. Connectors having no sharpened surfaces are desirable because the chances of inadvertently piercing the operator's skin are lessened.
However, some existing needleless connectors allow fluid flow in only one direction, or require some further manipulation after a connection is established to allow fluid flow in both directions. Both of these characteristics are undesirable because they limit the usefulness of the connector. A further concern in the design of needleless connectors is the order of occurrences in which the connection is made. For example, allowing fluid to escape or air to enter during connection due to the female connector being opened before the male connector is sufficiently seated are undesirable.
Additionally, some existing connectors accommodate a relatively large interior fluid volume, requiring injection of a commensurately large volume of fluid just to fill the connector. If not taken into account, this fluid volume can detract from the volume of medicament injected and may be clinically significant. An inconvenient separate flushing procedure may be required in low dose injections or in the injection of unstable medicines due to this relatively large interior volume.
Moreover, relatively complex geometries and provision of springs and the like in the wetted portion of the connector interior may give rise to "dead spaces", where fluid tends to linger due to poor flushing. Dead spaces give rise to problems similar to those occasioned by large interior volumes, again resulting in the inconvenient requirement of flushing.
A further concern regarding the design of a needleless connector is that it should not accommodate a conventional sharp needle. Where such connectors can be used with sharp and blunt cannulas, the deterrent effect with regard to using sharp needles to make fluid connections, with an associated reduction in the number of accidental needle sticks, is potentially compromised.
Furthermore, it is desirable that needleless connectors be configured so that they can be easily cleaned by an antiseptic wipe or otherwise sterilized prior to making a connection. All exterior surfaces that may be involved in the transmission of fluid should be available for cleaning prior to the connection being made. Some prior connectors have a small rift or fissure, defined by a clearance between parts or an elastomeric element that is not under sufficient compression, at the proximal or connecting end. Such a feature is difficult and inconvenient to clean in attempting to sterilize a connector. Alternatively, connectors requiring a cap to maintain a sterile connection port are undesirable because the extra steps of removing and replacing a cap are inconvenient for medical personnel.
Another important characteristic of a needleless connector is its ability to hold a vacuum from a distal side. That is to say, if a vacuum is applied to the interior of the connector, the connector should not admit air. This becomes an increased concern in connectors that have been used at least once. Adverse consequences may result if a connector cannot hold a vacuum, for example, some automated infusion pumps wall pull a vacuum in a tubing line under certain circumstances. Needlelees connectors that will not hold a vacuum, incorporated in an infusion get used with such a pump, may admit air when no connector or cap is attached, which may in turn cause a potentially harmful air embolism in a patient.
The ability to accommodate a high fluid flow rate is also desirable in a needleless connector. Physicians in certain situations order the administration of medicaments at high flow rates. Some prior connectors have restrictive geometries, which limit their flow capacity such that administering fluids at high rates is inconvenient for medical personnel. Often flow rate requirements cannot be met under gravity head flow conditions.
Lastly, some existing needleless connectors have a relatively complex configuration and large number of parts. Such connectors are difficult and costly to manufacture, and may have more problems in service, such as sticking due to the difficulty flushing medicaments from small dead spaces inherent in complex geometries referred to above.
Consequently, there is a continuing need, for a variety of reasons, for improvements in injection sites. The present invention fulfills this need.